Manwgan appears to have been a very
small boy when his father, Selyf Sarffgadau (Battle-Snake) was
killed at the Battle of Caer-Legion (Chester) in 613. One theory asserts
that this led to an invasion of Powys by Eluadd ap Glast (alias Eluan Powys),
the erstwhile King of Dogfeiling. The usurper probably managed to hold the
throne for some thirty years or more before he was killed fighting the
Northumbrians, possibly at the Battle of Maes-Cogwy (Oswestry) in 642. The
Dogfeiling dynasty was finally crushed by the Saxons around 656, and
Manwgan was able to take his rightful place on the Powysian throne.